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One-Roof Solar Evaluation

November, 2011

The cost to install
residential solar panels in the Washington DC area has dropped significantly in
the last two years. DC Solar United
Neighborhoods, a consortium of cooperatives, has completed a cost comparison by
inviting vendors to bid on the same job.
Four vendors participated in the bidding (Lighthouse Solar, Solar City,
Solar Solution and Astrum Solar), while several other vendors completed an
online survey . Our goal in presenting this information is to provide as much
relevant and unbiased information as possible to help you choose the installer
that’s right for you. We hope you find
this information helpful.

Meet
the Installers

To provide basic
information about installers in the area with which DCSUN is familiar, we conducted
a survey. The questions are meant to give you a general understanding of each
installer's capabilities and services. We asked installers to respond on topics
such as how long they've been in business, how much work they've done in the
District, what kind of certifications they have and what kind of financing they
offer. For survey results, click the link next to each participating installer
in the directory below.

Four companies chose
to compete in DC Sun’s One Roof Evaluation bidding process. Participating
installers were asked to come to the residence of the same Capitol Hill
homeowner and provide a bid. Besides comparing prices, having them all bid to
install a PV system on the same roof allows one to compare equipment, size,
installation and other options.

Lighthouse Solar, Solar City, Solar Solution and Astrum Solar submitted bids in
the order listed for purchasing a PV system. Solar City submitted three leasing
options for the same PV system. Astrum Solar submitted bids for three different
PV systems, varying the system size and installation method. Please note that
our reference bid project only represents a snapshot in time. Market
conditions, equipment pricing, and financial incentives are all subject to
change over time.

Here are some of the key findings from this process:

Gross system cost (before any
incentives) for purchasing a system averaged $25,061, ranging from $19,382
to $34,320.

Net system cost (after tax and
other incentives) for purchasing a system averaged $12,854, ranging from
$9,922 to $16,784. The reduced net costs factor in Federal tax
credits and solar Renewable Energy Credits (sRECs) that vendors will help
you leverage.

For the lease options, the
Initial System Cost averaged $3,639, ranging from $0 to $7,278. Two of the
lease options had annual payments, averaging $44/month, ranging from $516
to $816 per year.

Simple Payback for purchase
averaged 13 years, ranging from 12 to 15 years. For leasing, the average
was ~11 years, excluding the $0 down option.

Internal Rate of Return for
purchase averaged 5.8%, ranging from 4.6% to 7.5%. For leasing, the
average was 10.0%, excluding the $0 down option.

Reduction in the home's
electric use ranged from 92% to more than 100%. A smaller system can be
installed if the home is fully weatherized and has energy efficient
heating, cooling, lighting and appliances.

DC SUN suggests that
weatherization be done prior to, or in conjunction or directly after you
have completed your solar installations. If your solar
installation is linked with significant roof work-- you should definitely
take care of insulation and sealing the attic at the same time. DC SUN
also recommends that systems not be sized greater than 100% because
current DC laws do not allow you to take advantage of “overproduction”
that occurs over a year’s time frame -- unless you are planning on buying
an electric car in the near term that would consume your energy surplus.

This analysis does not take
into account the presence of any DC solar rebate.

To see the bid results
click on the link next to each participating installer in the directory below
or go here.

I Want to Run The Numbers Myself!

Great! To play with
the numbers and tailor them to your situation, check out this spreadsheet [Link to Andy's Spreadsheet].

Which Installer is Right for Me?

When looking for an
installer, we recommend you get 2 to 4 quotes to compare. Getting quotes from
more than one installer will help you better understand your needs and what
you're looking for in an installer. One size definitely does not fit all.
Choosing any contractor is a very personal experience. Don't be afraid to ask
questions and ask your installer to explain things to you. Whether you're
buying your system or leasing it, you're choosing a system that's going to last
for 20-30 years. You should feel comfortable with your choice.

Below is a list of all
the installers in the area which are known to DCSUN. For a complete list of
installers approved by DDOE, please see their list under "District-Area Renewable
Energy Contractors and Installers".

Thinking about going
solar? Tell ‘em DC SUN or your local solar coop sent you! Many local installers will make a donation to
DC SUN’s Community emPOWERment Fund if
their customer is a member of DC SUN. Money in the fund goes to support solar
projects for non-profits, churches, and other community organizations. So, when
you talk to an installer, tell ‘em DC SUN or your solar coop sent you! (Note:
DC SUN is 100% installer neutral. Installer participation in the emPOWERment
fund does not constitute an endorsement of the company.)